Moto Monster Overheating

I want to buil a 2DOF simulator but first I am trying to make at least one motor run.
The problem that I am having is trat the Sparkfun Moto Monster Shield is getting immediatly hot.
The shield is rated for 12V 30A (at least it is supposed to) and that is the output of the power supplyer
What am I doing wrong? Is the shield that is not intended for these purpose (too weak)? or the power supply is too powerfull? or the code is wrong?

Pls I need help before I fry the circuit

Code:

#include "MegaServo.h"

MegaServo megaServo;

void setup()
{
  Serial.begin(9600);
    
  megaServo.attach(7, 8, 5, A4);

  megaServo.write(90);
}

void loop()
{
  if (Serial.available())
  {
    int angle = Serial.parseInt();
    Serial.print("angle : ");
    Serial.print(angle);
    Serial.println("");
    
    megaServo.write(angle);
    delay(10);
  }
}
//https://www.instructables.com/id/Wiper-Motor-and-Arduino-Mega-Servo/

Thanks for suggestion.
The MM is original.
I'll let you know what was the problem if I manage to solve it

Not yet, I'm doing things with care and I am making sure that all connections are perfect before, I want to be sure that the problem is not caused by bad wiring and connections

The problem was caused by my connections. But now I have another problem :
It sets the initial position , as setup() says, then takes just the first command then stops, just keeps printing "?" on the consols.
I suppose that happends because of the potentiometer that moves slightly and loses track of the position.
PS: I tried to take a look at SMC3 guide but it looks a little complicated to me ( I am a web developer but I am a beginner at electronics)

I am for sure going to use SMC3 guide when I'll have a more precise idea of what to do , and I'll have everything wired up definitly. For the moment I am thinking if I should build just a platform for the seat (I have a few space) or a complete simulator but as small as I can . What do you suggest?

Thank, you have just saved me from a complete failure

I was thinking of building something like this to have a better leverage and sacrifice angle for torque in order to keep compact the simulator , I am making a 3d model of it to let you better understand what I am thinking to do

This might be the final shape of the simulator/platform